It's easy to forget today, but the Sega home consoles were always secondary to their arcade business. The main reason the Saturn sold even as well as it did was because it was the only way to play versions of the heavy hitters: Virtua Fighter, Virtua Racing, Daytona USA and Sega Rally in the home, in any fashion approaching the arcade (though still quite cut down). Those Sega 3D arcade games were absolutely mind blowing back in the early-mid 90s, and the pace of technical progress and new ideas was unlike anything since.
And the Dreamcast was conceived from day one to make it easy to port games from the Sega Naomi arcade system, and those arcade ports are probably the main reason people still play the Dreamcast to this day.